The standard deviation is a measure of how spread out your data are. It is useful in comparing sets of data which may have the same mean but a different range. Computation of the standard deviation is a bit tedious. The steps are:

  • Compute the mean for the data set.

  • Compute the deviation by subtracting the mean from each value.

  • Square each individual deviation.

  • Add up the squared deviations.

  • Divide by one less than the sample size.

  • Take the square root

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